Seminars

Jan
23
2018

Computer Science/Discrete Mathematics Seminar II

A Constant-factor Approximation Algorithm for the Asymmetric Traveling Salesman Problem
Ola Svensson
10:30am|S-101

We give a constant-factor approximation algorithm for the asymmetric traveling salesman problem. Our approximation guarantee is analyzed with respect to the standard LP relaxation, and thus our result confirms the conjectured constant integrality...

Jan
22
2018

Computer Science/Discrete Mathematics Seminar I

The Matching Problem in General Graphs is in Quasi-NC
Ola Svensson
11:00am|S-101

We show that the perfect matching problem in general graphs is in Quasi-NC. That is, we give a deterministic parallel algorithm which runs in polylogarithmic time on quasi-polynomially many processors. The result is obtained by a derandomization of...

Dec
12
2017

Computer Science/Discrete Mathematics Seminar II

A PSPACE construction of a hitting set for the closure of small algebraic circuits
Amir Shpilka
10:30am|S-101

We study the complexity of constructing a hitting set for the class of polynomials that can be infinitesimally approximated by polynomials that are computed by polynomial sized algebraic circuits, over the real or complex numbers. Specifically, we...

Dec
11
2017

Theoretical Machine Learning Seminar

Learning with little data
12:30pm|White-Levy Room

The current successes of deep neural networks have largely come on classification problems, based on datasets containing hundreds of examples from each category. Humans can easily learn new words or classes of visual objects from very few examples...

Dec
11
2017

Computer Science/Discrete Mathematics Seminar I

Recent advances in high dimensional robust statistics
Daniel Kane
11:00am|S-101

It is classically understood how to learn the parameters of a Gaussian even in high dimensions from independent samples. However, estimators like the sample mean are very fragile to noise. In particular, a single corrupted sample can arbitrarily...

Dec
05
2017

Computer Science/Discrete Mathematics Seminar II

Short proofs are hard to find (joint work w/ Toni Pitassi and Hao Wei)
Ian Mertz
10:30am|S-101

Proof complexity studies the problem computer scientists and mathematicians face every day: given a statement, how can we prove it? A natural and well-studied question in proof complexity is to find upper and lower bounds on the length of the...

Dec
04
2017

Computer Science/Discrete Mathematics Seminar I

General strong polarization
Madhu Sudan
11:00am|S-101

A martingale is a sequence of random variables that maintain their future expected value conditioned on the past. A $[0,1]$-bounded martingale is said to polarize if it converges in the limit to either $0$ or $1$ with probability $1$. A martingale...

Nov
28
2017

Computer Science/Discrete Mathematics Seminar II

Geometric complexity theory from a combinatorial viewpoint
10:30am|S-101

Geometric Complexity Theory (GCT) was developed by Mulmuley and Sohoni as an approach towards the algebraic version of the P vs NP problem, VP vs VNP, and, more generally, proving lower bounds on arithmetic circuits. Exploiting symmetries, it...

Nov
27
2017

Theoretical Machine Learning Seminar

Beyond log-concavity: provable guarantees for sampling multi-modal distributions using simulated tempering Langevin Monte Carlo
Holden Lee
12:30pm|White-Levy Room

A fundamental problem in Bayesian statistics is sampling from distributions that are only specified up to a partition function (constant of proportionality). In particular, we consider the problem of sampling from a distribution given access to the...